How does Hemingway show that Jake is insecure about his masculinity early in the novel?

Jake does not mention his insecurities directly. We must search for information about them in his reactions and descriptions of others. Jake takes a condescending attitude toward Cohn. His descriptions cast Cohn as a weak, inexperienced man. Jake’s contempt seems to arise partly from Cohn’s feminized status. He characterizes Cohn as timid and easily controlled by a strong woman like Frances. This emphasis on Cohn’s lack of masculinity can be seen as a reflection of Jake’s own insecurities about his manhood. Also, Jake resents the group of male friends with whom Brett dances at the club. His statements about them subtly imply that they are homosexuals. Brett can “safely” get drunk around them, for instance, because they have no interest in having sex with her. Jake realizes that he should be “tolerant,” but admits that he is in fact “disgusted” by them. His irrational disgust likely stems from his perception of them as unmanly, illustrating his worries about his own manliness. Thus, Hemingway uses Jake’s contempt for Cohn’s feeble masculinity and his reaction of abhorrence toward Brett’s homosexual friends to reveal his anxiety about his own masculinity.

Compare Jake’s relationship to Brett with Cohn’s relationship to Frances.

Jake adopts a patronizing attitude toward Cohn, especially when he describes Cohn’s interactions with women. Early in the novel, Frances dominates Cohn, and her wishes overrule his. Because of Frances’s domination of Cohn, Jake seems to lack respect for him. But Jake’s relationship with Brett is actually quite similar to that between Cohn and Frances. Jake is willing to do anything for Brett. He allows her to lean on him for emotional support and then abandon him for other men. He even helps facilitate her affair with Pedro Romero. Cohn eventually breaks with Frances; despite her verbal abuse, he is able to end his relationship with her. Jake, on the other hand, is too attached to Brett to ever let go of her, despite her mistreatment of him. Thus, in some ways, Cohn is stronger in his relationship with Frances than Jake is in his with Brett.

How is Count Mippipopolous like Jake and his friends? How is he different?

Like Jake and his friends, the count has seen a great deal of violence. He has survived seven wars and four revolutions. He is also an expatriate, a Greek man living abroad. Furthermore, he loves to seek pleasure, as do Jake and his friends. However, unlike the members of the Lost Generation, he seems to genuinely enjoy these pleasures. Jake and his friends are all engaged in an attempt to forget the war and their unhappiness by drinking themselves into oblivion while filling their spare time with social appointments. The count, on the other hand, delights in food, wine, and spending time with friends. These things satisfy him and make him happy. He covets Brett, but this desire does not torment him as it does Jake, Cohn, and Mike. He is content to enjoy her company when he can. Thus, while the count has essentially the same lifestyle as Jake and his friends, he derives joy from it while they do not, and he is not a victim of their disillusioned cynicism.